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MO_1_2478 - Risk of visual toxicity following fractionated proton vs photon radiation therapy for patients with meningiomas

Monday, October 22
10:45 AM - 12:15 PM
Location: Innovation Hub, Exhibit Hall 3

Risk of visual toxicity following fractionated proton vs photon radiation therapy for patients with meningiomas
A. J. Bishop1, K. T. Tran2, P. K. Allen3, A. Mahajan4, M. F. McAleer5, J. Li1, A. J. Ghia1, E. P. Sulman6, D. N. Yeboa7, F. DeMonte5, S. M. Raza8, D. R. Grosshans9, and S. L. McGovern5; 1Dept. of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, 2University of Texas Medical Branch at Galveston, Galveston, TX, 3Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, 4Department of Radiation Oncology, Mayo Clinic, Rochester, MN, 5The University of Texas MD Anderson Cancer Center, Houston, TX, 6University of Texas MD Anderson Cancer Center, Houston, TX, 7MD Anderson Cancer Center, Houston, TX, 8UT MD Anderson Cancer Center, Houston, TX, 9Baylor College of Medicine, Houston, TX

Purpose/Objective(s): To characterize the visual toxicities associated with proton beam therapy (PBT) or intensity modulated radiation therapy (IMRT) for the treatment of meningioma.

Materials/Methods: We reviewed the records of 136 patients treated with RT for meningioma at our institution between 2000 and 2014. Seventy-five (55%) patients received IMRT and 61 (45%) received PBT. Toxicities were graded using the Common Terminology Criteria for Adverse Events (CTCAE 4.03).

Results: Median follow-up time was 67 months (range, 0-190 months; IMRT 91 months vs. 54 months, P<0.001). Eighty seven (64%) patients had tumors involving the base of skull (BOS) (PBT 60% vs. IMRT 68%, P=0.29). There was no difference in the incidence of acute visual toxicities between PBT (n=9, 15%) and IMRT (n=6, 8%; P=0.27) with the two most common being eye irritation (n=6) and diploplia (n=4). Eight patients (6%) experienced an acute grade 1 visual toxicity and 7 a grade 2, with no differences between modalities (P=0.32). There were no grade 3 or higher acute visual toxicities. Thirty seven (27%) patients had at least one late toxicity, the majority of which were grade 1-2 (n=24, 65%); we identified 11 patients (8%) with grade 3 toxicity, 2 (1.5%) with grade 4, and none with grade 5. Of those, 13 patients (48%, 10% of cohort) developed a late visual toxicity (PBT n=10 vs. IMRT n=3, P=0.02) with a median time of 20 months (range, 7-130 months; PBT 20 months vs. IMRT 25 months, P=0.50), of which 6 were grade 2 (46%), 5 were grade 3 (38%), and 2 were grade 4 (16%). Seven (54%) of the late visual toxicities were decreased visual acuity (grade 2=4; grade 3=1; grade 4=2) (PBT n=6, 10% vs. IMRT n=1, 1.3%; P=0.045), and all occurred in patients receiving treatment for BOS meningiomas. The median ipsilateral optic nerve or chiasm Dmax for patients who experienced loss of visual acuity was 5132 cGyRBE (range, 4931-5516 cGyRBE), which was not significantly different from patients with BOS meningiomas not experiencing a decline in visual acuity (median, 5161 cGyRBE, P=0.47). There were 3 patients with clinically diagnosed optic neuropathy (PBT n=2 both grade 4, IMRT n=1 grade 3), of which all had tumors involving the cavernous sinus or optic nerve; however, none had an optic nerve and/or optic chiasm Dmax above 54 GyRBE. The other late visual toxicities included cataracts (PBT n=1 vs IMRT n=2, all grade 3), dry eye (PBT n=2, all grade 2) and a retinopathy (PBT n=1, grade 3).

Conclusion: The overall risk of high grade late toxicities is low following RT for patients with meningioma. However, for patients with BOS tumors, there is a risk of decreased visual acuity and/or optic neuropathy that is not correlated with Dmax. Further dosimetric analyses are warranted.

Author Disclosure: A.J. Bishop: None. K.T. Tran: None. P.K. Allen: None. A. Mahajan: Secretary; PTCOG-NA. Membership; PROS. M. McAleer: Honoraria; PREX S. p. A, AOSpine, Osler Institute. Speaker's Bureau; Osler Institute. Travel Expenses; Osler Institute. J. Li: Research Grant; BMS, Medtronic. Travel Expenses; Elekta. E.P. Sulman: Website/Technology Committee Chair; Society for Neuro-Oncology. D.N. Yeboa: Travel Expenses; Eli Lilly. D.R. Grosshans: None. S.L. McGovern: Independent Contractor; MD Anderson Physicians Network. Honoraria; American College of Radiology. Travel Expenses; American College of Radiology.

Andrew Bishop, MD

Disclosure:
Employment
MD Anderson Cancer Center: Employee: Employee

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